Taking a folic acid pill a day - a simple measure to prevent severe birth defects - is under-promoted in the media, under-recommended by health-care providers, and under-used by women of childbearing age, according to a review of studies.

Less than one-fourth of women who are aware of the importance of folic acid take supplements daily in accordance with public-health guidelines, says Corina Mihaela Chivu, lead author of the systematic review, which appeared earlier this year in an issue of the American Journal of Health Promotion.

Chivu and her co-authors reviewed 31 studies conducted between 1992 and 2005 designed to increase awareness, knowledge, and consumption of folic acid before and during pregnancy. The studies used television, Internet, brochures, counseling, posters, newspapers, and magazines to provide information about folic acid to women. The data encompassed some 23,000 women ages 15 to 49, Chivu says.

Overall, researchers found that receiving information increased awareness and knowledge: 60 percent of women were aware of the role of folic acid before the interventions, while 72 percent were aware of it afterward. Knowledge, however, didn't necessarily translate to action: 14 percent took folic acid before the intervention; only 23 percent started taking it afterward.

What will help the message sink in?

The role of the mass media and health professionals is crucial, says Chivu, a physician who was with the National Institute for Research and Development in Health, in Bucharest, Romania, when the review took place.

"For the last six months in the U.S., no advertisement about folic acid in pregnancy has appeared on TV," Chivu says. "Instead, ads promoting expensive and ineffective drugs appear daily."

Chivu, now with the Centre for Public Health Research at Brunel University, in London, was surprised to learn that "interventions within national campaigns didn't persuade health professionals about the importance of counseling women on folic acid."

A study in the Netherlands showed 25 percent of health professionals never advised women about folic acid, she adds.

Similarly, a March of Dimes Gallup Survey in 2007 showed that of those aware of folic acid, only one-third said they had heard about it from a health provider. That was up, however, from just 13 percent in 1995. In the latest survey, another 31 percent said they had read about folic acid in magazines, and 23 percent said they received the news from radio or TV.

Folic acid, a form of vitamin B, occurs in green plants, fresh fruit, liver, and yeast. U.S. Public Health Service guidelines call for women of childbearing age to take 400 micrograms of folic acid daily. Health officials say women should take folic acid for two months before pregnancy and during the first three months of pregnancy.

Taking folic acid can help prevent specific neural tube defects, according to the March of Dimes. The neural tube is an embryonic structure that develops into the brain and spinal cord. Spina bifida, one of the two most common neural tube defects, is a condition in which there is exposure of part of the spinal cord and its coverings. The other is anencephaly, in which a large portion of the child's brain is missing.

The U.S. Food and Drug Administration and the Department of Health and Human Services have promoted fortification of enriched cereal grain products with folic acid. This has apparently been successful in reducing neural tube defects in the United States, as well as in Canada," the authors say, adding that results might justify a decision to fortify flour in other countries.

Folic-acid fortification is a step forward, Chivy says. Still, she adds, "Fortification is not a surrogate for supplementation."

In 2007, a study from the Centers for Disease Control and Prevention found a decrease of 8 percent to 16 percent in folate levels in U.S. women of childbearing age. It based the finding on blood-draw surveys conducted between 1999 and 2004. Health officials speculated that popular, low-carbohydrate diets might be causing the decline.

"Women who plan a pregnancy should eat foods rich in folate or fortified products, but at the same time take the pills with folic acid," Chivu says.

The review's findings are consistent with the experiences of health advocates. More women have heard about the importance of taking folic acid supplements; yet, "we're not where we should be" in terms-of consumption, says Joann Petrini, director of the perinatal data center for the March of Dimes. The organization has encouraged women to take supplements, and she says the new review offers more data undergirding this message.

"The leading reason (women did not take the supplement) was that they forgot," Petrini says. "Some said they didn't need them - they are not planning a pregnancy - but we know that half of pregnancies are unplanned ... half. That reinforces the idea that you may not be thinking about it, but it may happen."